linux.git/arch/x86/kernel/cpu/mshyperv.c, branch v3.17 Linux kernel source tree x86, irq, pic: Probe for legacy PIC and set legacy_pic appropriately 2014-04-14T18:49:55+00:00 K. Y. Srinivasan kys@microsoft.com 2014-04-14T18:43:49+00:00 e179f6914152eca9b338e7d8445684062f560c55 The legacy PIC may or may not be available and we need a mechanism to detect the existence of the legacy PIC that is applicable for all hardware (both physical as well as virtual) currently supported by Linux. On Hyper-V, when our legacy firmware presented to the guests, emulates the legacy PIC while when our EFI based firmware is presented we do not emulate the PIC. To support Hyper-V EFI firmware, we had to set the legacy_pic to the null_legacy_pic since we had to bypass PIC based calibration in the early boot code. While, on the EFI firmware, we know we don't emulate the legacy PIC, we need a generic mechanism to detect the presence of the legacy PIC that is not based on boot time state - this became apparent when we tried to get kexec to work on Hyper-V EFI firmware. This patch implements the proposal put forth by H. Peter Anvin <hpa@linux.intel.com>: Write a known value to the PIC data port and read it back. If the value read is the value written, we do have the PIC, if not there is no PIC and we can safely set the legacy_pic to null_legacy_pic. Since the read from an unconnected I/O port returns 0xff, we will use ~(1 << PIC_CASCADE_IR) (0xfb: mask all lines except the cascade line) to probe for the existence of the PIC. In version V1 of the patch, I had cleaned up the code based on comments from Peter. In version V2 of the patch, I have addressed additional comments from Peter. In version V3 of the patch, I have addressed Jan's comments (JBeulich@suse.com). In version V4 of the patch, I have addressed additional comments from Peter. Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Link: http://lkml.kernel.org/r/1397501029-29286-1-git-send-email-kys@microsoft.com Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> 
The legacy PIC may or may not be available and we need a mechanism to
detect the existence of the legacy PIC that is applicable for all
hardware (both physical as well as virtual) currently supported by
Linux.

On Hyper-V, when our legacy firmware presented to the guests, emulates
the legacy PIC while when our EFI based firmware is presented we do
not emulate the PIC. To support Hyper-V EFI firmware, we had to set
the legacy_pic to the null_legacy_pic since we had to bypass PIC based
calibration in the early boot code. While, on the EFI firmware, we
know we don't emulate the legacy PIC, we need a generic mechanism to
detect the presence of the legacy PIC that is not based on boot time
state - this became apparent when we tried to get kexec to work on
Hyper-V EFI firmware.

This patch implements the proposal put forth by H. Peter Anvin
<hpa@linux.intel.com>: Write a known value to the PIC data port and
read it back. If the value read is the value written, we do have the
PIC, if not there is no PIC and we can safely set the legacy_pic to
null_legacy_pic. Since the read from an unconnected I/O port returns
0xff, we will use ~(1 << PIC_CASCADE_IR) (0xfb: mask all lines except
the cascade line) to probe for the existence of the PIC.

In version V1 of the patch, I had cleaned up the code based on comments from Peter.
In version V2 of the patch, I have addressed additional comments from Peter.
In version V3 of the patch, I have addressed Jan's comments (JBeulich@suse.com).
In version V4 of the patch, I have addressed additional comments from Peter.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Link: http://lkml.kernel.org/r/1397501029-29286-1-git-send-email-kys@microsoft.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-04-01T18:22:57+00:00 Linus Torvalds torvalds@linux-foundation.org 2014-04-01T18:22:57+00:00 683b6c6f82a60fabf47012581c2cfbf1b037ab95 Pull irq code updates from Thomas Gleixner: "The irq department proudly presents: - Another tree wide sweep of irq infrastructure abuse. Clear winner of the trainwreck engineering contest was: #include "../../../kernel/irq/settings.h" - Tree wide update of irq_set_affinity() callbacks which miss a cpu online check when picking a single cpu out of the affinity mask. - Tree wide consolidation of interrupt statistics. - Updates to the threaded interrupt infrastructure to allow explicit wakeup of the interrupt thread and a variant of synchronize_irq() which synchronizes only the hard interrupt handler. Both are needed to replace the homebrewn thread handling in the mmc/sdhci code. - New irq chip callbacks to allow proper support for GPIO based irqs. The GPIO based interrupts need to request/release GPIO resources from request/free_irq. - A few new ARM interrupt chips. No revolutionary new hardware, just differently wreckaged variations of the scheme. - Small improvments, cleanups and updates all over the place" I was hoping that that trainwreck engineering contest was a April Fools' joke. But no. * 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (68 commits) irqchip: sun7i/sun6i: Disable NMI before registering the handler ARM: sun7i/sun6i: dts: Fix IRQ number for sun6i NMI controller ARM: sun7i/sun6i: irqchip: Update the documentation ARM: sun7i/sun6i: dts: Add NMI irqchip support ARM: sun7i/sun6i: irqchip: Add irqchip driver for NMI controller genirq: Export symbol no_action() arm: omap: Fix typo in ams-delta-fiq.c m68k: atari: Fix the last kernel_stat.h fallout irqchip: sun4i: Simplify sun4i_irq_ack irqchip: sun4i: Use handle_fasteoi_irq for all interrupts genirq: procfs: Make smp_affinity values go+r softirq: Add linux/irq.h to make it compile again m68k: amiga: Add linux/irq.h to make it compile again irqchip: sun4i: Don't ack IRQs > 0, fix acking of IRQ 0 irqchip: sun4i: Fix a comment about mask register initialization irqchip: sun4i: Fix irq 0 not working genirq: Add a new IRQCHIP_EOI_THREADED flag genirq: Document IRQCHIP_ONESHOT_SAFE flag ARM: sunxi: dt: Convert to the new irq controller compatibles irqchip: sunxi: Change compatibles ... 
Pull irq code updates from Thomas Gleixner:
 "The irq department proudly presents:

   - Another tree wide sweep of irq infrastructure abuse.  Clear winner
     of the trainwreck engineering contest was:
         #include "../../../kernel/irq/settings.h"

   - Tree wide update of irq_set_affinity() callbacks which miss a cpu
     online check when picking a single cpu out of the affinity mask.

   - Tree wide consolidation of interrupt statistics.

   - Updates to the threaded interrupt infrastructure to allow explicit
     wakeup of the interrupt thread and a variant of synchronize_irq()
     which synchronizes only the hard interrupt handler.  Both are
     needed to replace the homebrewn thread handling in the mmc/sdhci
     code.

   - New irq chip callbacks to allow proper support for GPIO based irqs.
     The GPIO based interrupts need to request/release GPIO resources
     from request/free_irq.

   - A few new ARM interrupt chips.  No revolutionary new hardware, just
     differently wreckaged variations of the scheme.

   - Small improvments, cleanups and updates all over the place"

I was hoping that that trainwreck engineering contest was a April Fools'
joke.  But no.

* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (68 commits)
  irqchip: sun7i/sun6i: Disable NMI before registering the handler
  ARM: sun7i/sun6i: dts: Fix IRQ number for sun6i NMI controller
  ARM: sun7i/sun6i: irqchip: Update the documentation
  ARM: sun7i/sun6i: dts: Add NMI irqchip support
  ARM: sun7i/sun6i: irqchip: Add irqchip driver for NMI controller
  genirq: Export symbol no_action()
  arm: omap: Fix typo in ams-delta-fiq.c
  m68k: atari: Fix the last kernel_stat.h fallout
  irqchip: sun4i: Simplify sun4i_irq_ack
  irqchip: sun4i: Use handle_fasteoi_irq for all interrupts
  genirq: procfs: Make smp_affinity values go+r
  softirq: Add linux/irq.h to make it compile again
  m68k: amiga: Add linux/irq.h to make it compile again
  irqchip: sun4i: Don't ack IRQs > 0, fix acking of IRQ 0
  irqchip: sun4i: Fix a comment about mask register initialization
  irqchip: sun4i: Fix irq 0 not working
  genirq: Add a new IRQCHIP_EOI_THREADED flag
  genirq: Document IRQCHIP_ONESHOT_SAFE flag
  ARM: sunxi: dt: Convert to the new irq controller compatibles
  irqchip: sunxi: Change compatibles
  ...
x86, hyperv: Bypass the timer_irq_works() check 2014-03-27T18:02:45+00:00 Jason Wang jasowang@redhat.com 2014-02-28T03:30:29+00:00 ca3ba2a2f4a49a308e7d78c784d51b2332064f15 This patch bypass the timer_irq_works() check for hyperv guest since: - It was guaranteed to work. - timer_irq_works() may fail sometime due to the lpj calibration were inaccurate in a hyperv guest or a buggy host. In the future, we should get the tsc frequency from hypervisor and use preset lpj instead. [ hpa: I would prefer to not defer things to "the future" in the future... ] Cc: K. Y. Srinivasan <kys@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: <stable@vger.kernel.org> Acked-by: K. Y. Srinivasan <kys@microsoft.com> Signed-off-by: Jason Wang <jasowang@redhat.com> Link: http://lkml.kernel.org/r/1393558229-14755-1-git-send-email-jasowang@redhat.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> 
This patch bypass the timer_irq_works() check for hyperv guest since:

- It was guaranteed to work.
- timer_irq_works() may fail sometime due to the lpj calibration were inaccurate
  in a hyperv guest or a buggy host.

In the future, we should get the tsc frequency from hypervisor and use preset
lpj instead.

[ hpa: I would prefer to not defer things to "the future" in the future... ]

Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: <stable@vger.kernel.org>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: http://lkml.kernel.org/r/1393558229-14755-1-git-send-email-jasowang@redhat.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
x86: hyperv: Fixup the (brain) damage caused by the irq cleanup 2014-03-05T12:42:14+00:00 Thomas Gleixner tglx@linutronix.de 2014-03-05T12:42:14+00:00 76d388cd72ab08c2c56b1e2bd430e7422fc40168 Compiling last minute changes without setting the proper config options is not really clever. Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
Compiling last minute changes without setting the proper config
options is not really clever.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
x86: hyperv: Fix brown paperbag typos reported by Fenguangs build robot 2014-03-04T22:53:33+00:00 Thomas Gleixner tglx@linutronix.de 2014-03-04T22:51:34+00:00 13b5be56d1c5ed302df53f6dfbe19b9f4e3fd3ce Reported-by: fengguang.wu@intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: K. Y. Srinivasan <kys@microsoft.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: linuxdrivers <devel@linuxdriverproject.org> Cc: x86 <x86@kernel.org> 
Reported-by: fengguang.wu@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linuxdrivers <devel@linuxdriverproject.org>
Cc: x86 <x86@kernel.org>
x86: hyperv: Make it build with CONFIG_HYPERV=m again 2014-03-04T22:41:44+00:00 Thomas Gleixner tglx@linutronix.de 2014-03-04T22:39:58+00:00 3c433679ab666fb76a9399679819a303989e8ead Commit 1aec16967 (x86: Hyperv: Cleanup the irq mess) removed the ability to build the hyperv stuff as a module. Bring it back. Reported-by: fengguang.wu@intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: K. Y. Srinivasan <kys@microsoft.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: linuxdrivers <devel@linuxdriverproject.org> Cc: x86 <x86@kernel.org> 
Commit 1aec16967 (x86: Hyperv: Cleanup the irq mess) removed the
ability to build the hyperv stuff as a module. Bring it back.

Reported-by: fengguang.wu@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linuxdrivers <devel@linuxdriverproject.org>
Cc: x86 <x86@kernel.org>
x86: Hyperv: Cleanup the irq mess 2014-03-04T16:37:54+00:00 Thomas Gleixner tglx@linutronix.de 2014-02-23T21:40:22+00:00 1aec169673d7db113c37367bbc371c2ba8109f06 The vmbus/hyperv interrupt handling is another complete trainwreck and probably the worst of all currently in tree. If CONFIG_HYPERV=y then the interrupt delivery to the vmbus happens via the direct HYPERVISOR_CALLBACK_VECTOR. So far so good, but: The driver requests first a normal device interrupt. The only reason to do so is to increment the interrupt stats of that device interrupt. For no reason it also installs a private flow handler. We have proper accounting mechanisms for direct vectors, but of course it's too much effort to add that 5 lines of code. Aside of that the alloc_intr_gate() is not protected against reallocation which makes module reload impossible. Solution to the problem is simple to rip out the whole mess and implement it correctly. First of all move all that code to arch/x86/kernel/cpu/mshyperv.c and merily install the HYPERVISOR_CALLBACK_VECTOR with proper reallocation protection and use the proper direct vector accounting mechanism. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: K. Y. Srinivasan <kys@microsoft.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: linuxdrivers <devel@linuxdriverproject.org> Cc: x86 <x86@kernel.org> Link: http://lkml.kernel.org/r/20140223212739.028307673@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
The vmbus/hyperv interrupt handling is another complete trainwreck and
probably the worst of all currently in tree.

If CONFIG_HYPERV=y then the interrupt delivery to the vmbus happens
via the direct HYPERVISOR_CALLBACK_VECTOR. So far so good, but:

  The driver requests first a normal device interrupt. The only reason
  to do so is to increment the interrupt stats of that device
  interrupt. For no reason it also installs a private flow handler.

  We have proper accounting mechanisms for direct vectors, but of
  course it's too much effort to add that 5 lines of code.

  Aside of that the alloc_intr_gate() is not protected against
  reallocation which makes module reload impossible.

Solution to the problem is simple to rip out the whole mess and
implement it correctly.

First of all move all that code to arch/x86/kernel/cpu/mshyperv.c and
merily install the HYPERVISOR_CALLBACK_VECTOR with proper reallocation
protection and use the proper direct vector accounting mechanism.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linuxdrivers <devel@linuxdriverproject.org>
Cc: x86 <x86@kernel.org>
Link: http://lkml.kernel.org/r/20140223212739.028307673@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
x86, hyperv: Move a variable to avoid an unused variable warning 2013-11-06T18:02:05+00:00 H. Peter Anvin hpa@zytor.com 2013-11-06T18:00:05+00:00 4c08edd305019061bf1ac95ce089497bdbb8b8ac The variable hv_lapic_frequency causes an unused variable warning if CONFIG_X86_LOCAL_APIC is disabled. Since the variable is only used inside a small if statement, move the declaration of that variable into the if statement itself. Cc: K. Y. Srinivasan <kys@microsoft.com> Link: http://lkml.kernel.org/r/1381444224-3303-1-git-send-email-kys@microsoft.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> 
The variable hv_lapic_frequency causes an unused variable warning if
CONFIG_X86_LOCAL_APIC is disabled.  Since the variable is only used
inside a small if statement, move the declaration of that variable
into the if statement itself.

Cc: K. Y. Srinivasan <kys@microsoft.com>
Link: http://lkml.kernel.org/r/1381444224-3303-1-git-send-email-kys@microsoft.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
x86, hyperv: Fix build error due to missing <asm/apic.h> include 2013-10-30T22:37:47+00:00 David Rientjes rientjes@google.com 2013-10-11T23:07:31+00:00 d68ce0177c1e51fb332369e0c99852a6d05668af 9e7827b5ea4c ("x86, hyperv: Get the local APIC timer frequency from the hypervisor") breaks the build with some configs because apic.h isn't directly included: arch/x86/kernel/cpu/mshyperv.c: In function 'ms_hyperv_init_platform': arch/x86/kernel/cpu/mshyperv.c:90:3: error: 'lapic_timer_frequency' undeclared (first use in this function) arch/x86/kernel/cpu/mshyperv.c:90:3: note: each undeclared identifier is reported only once for each function it appears in Fix it by including asm/apic.h. Signed-off-by: David Rientjes <rientjes@google.com> Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1310111604160.31170@chino.kir.corp.google.com Acked-by: K. Y. Srinivasan <kys@microsoft.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> 
9e7827b5ea4c ("x86, hyperv: Get the local APIC timer frequency from the
hypervisor") breaks the build with some configs because apic.h isn't
directly included:

arch/x86/kernel/cpu/mshyperv.c: In function 'ms_hyperv_init_platform':
arch/x86/kernel/cpu/mshyperv.c:90:3: error: 'lapic_timer_frequency' undeclared (first use in this function)
arch/x86/kernel/cpu/mshyperv.c:90:3: note: each undeclared identifier is reported only once for each function it appears in

Fix it by including asm/apic.h.

Signed-off-by: David Rientjes <rientjes@google.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1310111604160.31170@chino.kir.corp.google.com
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
x86, hyperv: Correctly guard the local APIC calibration code 2013-10-10T22:21:38+00:00 K. Y. Srinivasan kys@microsoft.com 2013-10-10T22:30:24+00:00 90ab9d5510932e146a9443bf5a591f95d5b5ada8 The code that gets the local APIC timer frequency from the hypervisor rather depends on there being a local APIC. Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Link: http://lkml.kernel.org/r/1381444224-3303-1-git-send-email-kys@microsoft.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> 
The code that gets the local APIC timer frequency from the hypervisor
rather depends on there being a local APIC.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Link: http://lkml.kernel.org/r/1381444224-3303-1-git-send-email-kys@microsoft.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>